Amway.com finished second behind HPShopping.com in Internet Explorer tests with 99.97% availability. Gap.com (99.95%) was next, followed by Overstock.com (99.90%), and CDW.com and OfficeDepot.com (tied at 99.89%).

In Firefox testing, five retailers (Gap.com, HPShopping.com, HSN.com, Overstock.com, Williams-Sonoma.com) tied in second place behind Toysrus.com with a 99.99% availability score for the month.

The average Internet Explorer availability score among the 19 retailers measured in August was 99.55%. The same group of retailers produced an average Firefox score of 99.65%.

Availability is determined by the percentage of tests that load correctly.